Electrical equipment for gauges



J. W. PLACE El AL ELECTRICAL EQUIPMENT FOR GAUGES VJuly 16, 1935.

Filed Jan. 21, 1952 2 Sheets-Sheet 1 NLM? W w QN w/ mi k Sw NN Quim@ Cfttorneg July 16, 1935- J. w. PLACE Er AL ELECTRICAL EQUIPMENT FOR GAUGES 2 Sheets-Sheet 2 Filed Jan. 2l, 1932 @muli-v Gttcmlega Patented July 16, 1935 UNITED STATES PATENT OFFICE ELECTRICAL EQUIPMENT FOR GAUGES Application January 21, 1932, Serial No. 588,020

2 Claims.

This invention relates to electrical equipment for gauges and, more particularly, is concerned ywith electric circuits utilized to indicate a predeterminedk condition of the medium to which a j gauge is responsive; and to prevent any liquid, with which the gauge may be associated, from congealing or becoming too viscous.

'I'he present invention is especially concerned with pressure-responsive instruments such, for

'10 example, as the differential pressure gauge disclosed in copending application, Serial Number 471,562, iled July 29, 1930. A portion of the gauge structure of that application is reproduced here for purpose of illustration and will be described later.

Itis a major object of the present invention to provide a new and improved signaling or indicating mechanism for association with a gauge. In this connection, it is an important object to l provide the signaling mechanism with means for conveniently and accurately adjusting it for re- .sponse toV any one of a large number of operating lconditions to which the gauge may be subjected, andto provide means for easily locking the adjusting means against inadvertent movement.

In some types of gauges it may be desirable to insert an air trap between the pressure-responsive element and the source of fluid supply. If the fluid comprises a corrosive liquid it should be kept out of contact with the gauge parts, and

if the liquid carries any sediment in suspension care should be taken to prevent the deposition and accumulation of this foreign matter within the gaugev structure. For example, in the above 23,5 v mentioned copending application, Serial Number 471,562, there is disclosed and claimed a differential pressure gauge embodying air traps in communication with a pair of bellows and to which a pair of fluid lines are connected. The uid lines y4,1) may be connected into a liquid flow line 'at different `points to cause the instrument to function as a ow indicator. The air traps prevent the liquid from reaching the bellows, but some of the liquid may enter the air traps or chambers and become liable to freeze or stiften therein and thus either render the instrument inoperative or decrease its sensitivity and speed of indication.

It is one of the main objects of the present invention to equip a gauge with an electrical unit for preventing any static associated liquid from freezing or `becoming too viscous, and especially to provide a heating circuit for incorporation in r a differential pressure gauge of the character l above discussed.

:#5- These ,and other objects of this invention will fully appear from a study of the following detailed description and appended claims, when taken in conjunction with the accompanying drawings, wherein:

Figure l represents a vertical longitudinal sec- 5 tion taken centrally of one embodiment of the present invention.

Figure 2 is a race view of a further structural embodiment of this invention, with a portion of the cover plate broken away.

Figure 3 is a side view, in partial section, of the device seen in Figure 2, with the pressureresponsive mechanism removed for clarity of illustration, and with the revealed internal mechanism slightly enlarged for the same reason.

Figure 4 is a horizontal sectional View of the device of Figures 2 and 3, as seen when looking upon the piane of line 4-4 of Figure 3 in the direction of the arrows.

Figure 5 constitutes a diagrammatic illustration of the electrical circuits employed in the signaling and heating systems of the other views.

With continued reference to the drawings, wherein like numerals are employed to designate like parts, and with particular reference for the moment to that form of invention illustrated in Figure 1 but which in most respects is substantially the same as the embodiment of the other views:

The numeral 6 designates a supporting block the form of a casting having a pair of yertically spaced lugs .l on one of its sides. A pair of chambers 8 and 9 are formed in the opposite side of the block to provide air traps, these chambers being designed for connection with a source ror sources of iiuid pressure by Way of ports l0. A passage l2 is provided in the casting between the chamber 8 vand the lower face of the upper lug 1, this passage opening into said chamber at ythe top thereof in order that only clean entrapped airmay serve to transmit pressures from the chamber to a corresponding pressure-responsive bellows assembly I3 that is secured to the upper lug 1. Inlike manner a passageway I4 opens into the top of the chamber 9 and extends through the lower lug 'l into communication with a second pressure-responsive assembly i3 carried by the latter.

The bellows assemblies I3 are aligned and interconnected by a threaded bolt l5 to form a differential pressure-responsive mechanism. An arm i6, forming a part of an indicating movement about to be described, is clamped upon the bolt I5 -for reciprocation therewith in response Vto variations in the diierential pressures. When `the pressures in the chambers 8 and 9 (and hence engaged and contact will be madewhen the -of non-conducting material 35. stripsV and sheets is clamped against the leg by in the bellows assemblies) are equal, no movement of thebolt and arm takes place, but if one pressure exceeds the other, the bolt and arm will be moved in a direction corresponding to the greater thrust and with a magnitude proportionate to the pressure differential. The mechanism actuated by the arm It is alike in both illustrated embodiments and hence reference will now be had to Figure 2 as well as Figure 1, for a brief description of that mechanism.

The movement mechanism comprises a rod Il connected to the arm l5 and hence designed to reciprocate in response to movement of the latter; and a pointer actuating lever I8 pivoted between its ends at I9, flexibly connected to the rod at one end as at 23 and having its other end freely engaging the curved tail arm 22 of a pointer 23 that is pivoted upon the block by a spindle '211.

The pointer therefore oscillates as the lever I8 swings about its fixed pivot I9 in response to reciprocation ofthe rod Il in one direction. A

hair springV 25 imparts movement to the pointed *in the opposite direction. A scale 23 is provided to indicate the degree of pointer oscillation, this scale being supported on the block -by a post 21.

A cover -28 is provided for cooperation with the block to house the movement and the pressure- `responsive mechanism. This housing has a window 29 through which the pointer and scale readings may be viewed.

An electrical signaling system preferably is associated with the instrument to render a visible or audible signal at a point outside or remote from the instrument -for the purpose of indicating that a predetermined pressure dierential exists. `As illustrated in both formsk of the invention, an L-shaped bracket bar comprising vertical and horizontal legs 3B and 32 respectively, is pivoted upon the block 6 by a screw and washer assembly 33. 'I'he leg 32 has a pair of iiexible copper strips 34 mounted on its free end, these strips being spaced and insulated with respect to each other and the leg by a number of small sheets The assembly of screws 36, with the free ends of the strips projecting to a position adjacent the bolt i5. The secured ends of the strips are connected with a pair of `feed wires 3l housed within a conduit 38 that is led into the housing by way of a coupling f element 39 which is screwed into the block 6.

Alhefree ends of the copper strips arefprovided with complemental contact points 40 which, when brought into engagement will close a circuit and thus actuate a signal or alarm device at some point outside the instrument. For example, in Figvure 5 there is schematically illustrated a circuit are adapted to be brought together'when a predetermined pressure differential exists. For example, in the drawings thepoints are about to be pointer reaches zero position because of the pressure exerted against one of the copper strips 34 v by an actuating stem 43 rigidly carried by the bolt !5.f 'I'he stem is sheathed by a rubber sleeve A lli to prevent short-circuiting. Obviously, the

actuating stem may be rearranged, if desired, to close the contactgap when Ythe pressure difby the latter may be swung to vary the relativeV positions of the copper strips 34 and the stem 53. The free end of the pivoted leg 35 of the bracket bar is provided with a slot 45 which receives a rotatable cylindrical cam 46. The cam Y operating mechanisms differ in the two forms of the invention and hence will be separately de-` scribed.

In that embodiment illustrated in Figures 2 and 3 the cam 5, fitted in the fork formed by the slot 35, is formed integral with, 'and eccentric to, a stem di.V The latter has a split end set into the block 5 with a tight frictional Vfit to yieldingly resist rotation of the stem, and an annular shoulder ,d is formed on the stem adjacent the cam for engagement with the block 6. The outer or free end of the stem Si has a cross-slot 5D for cooperation with a screw driver, whereby Vthe stem may be turned to rotate the cam 45. Shifting of this eccentric cam causes the leg 30 to swing about its pivot and thus move the copper blades 34 toward or away from the rubber sleeve of the actuating stem t3.

Means are provided for locking the eccentric cam i5 against rotation relative to the forked arm 3B, as follows: The outer end of the stem 41 is externally threaded at 52 to receive the internallythreaded end of a locking sleeve 53 which surrounds the stem. The outer end of this sleeve has a hexagonal head 5ft for cooperation with a tool to screw or unscrew the sleeve axially of the stem. A locking washer 55, recessed on one side at 55 to permit unhampered adjustment of the cam 15, is positioned between the sleeve 53 and the stem shoulder t9, the edge of the recessed side of the washer being in contact with the forked end of the bracket arm 38. After each adjustment of the stem lil, the sleeve 53 may be tightened to draw the shoulder 139 and washer 55 axially toward each other into rm engagement with the forked arm, thus to lock the stem 4l against rotation and at the same time to lock the arm against swinging movement with respect to the block 6 (in which the stem end 48 is mounted without lateral play). f

The stem lll and sleeve 5 3 are sufliciently elongated to have the slot 5l and head 54 respectively located in positions for convenient manipulation by tools from the outside of the cover plate 28. To this end the cover 28 is apertured and provided with a small cap-5carried on a chain 58 and detachably tted within the aperture to close the latter after each adjusting operation.

The adjusting mechanism, of the modied form disclosed in Figure 1, differs from that already described only in that no positive lock is provided and that the outer lend of the adjusting stud, ME), is disposed wholly within the housing and hence not readily subject to tampering or inadvertent rotation. There is a hole 59 in the cover in alignment with the stud and through which a screw driver may be inserted for conveniently aC- complishing the adjusting operation without removal of the cover 28.V A resilient pivoted closure element 6B normally is swung and snapped'into position to close the hole 5S. The frictional resistances Vof the pivotaldevices 33 and 48 are` relied upon to prevent undesired rotation of the cam 46 and bracket arm 30.

The rear side of the block 6 has lugs B2 which receive stud bolts 63 that cooperate with bars 64 to clamp thc instrument upon a support such, Ior example, as a portion 65 of a liquid ilow line. (See Figures 3 and 4.) When operating in this vertical position, there may be some liquid standing in the lower ends of the trap chambers 8 and S; and when the instrument is disposed in an atmosphere of low temperature, this standing liquid may become either so viscous as to retard the transmission of pressurey Variations to the pressure-responsive mechanism, or congealed to render the instrument completely inoperative. Means is provided to prevent these undesirable results, as follows.

As seen in Figures 3 and 4, a, vertical channel S6 is formed or recessed in the cast block 6 in such manner that it closely parallels the aligned air chambers 8, 9, and opens directly outwardly through the rear face of the block. A single elongated electrical resistance unit B1 is inserted laterally oi the channel and is shaped to fit snugly within the trough of the latter so as to transmit heat eiiiciently to the chambers 8, 9 by way of the relatively thin wall 68 which separates the latter from the channel. An asbestos packing 69 is held against the heating unit by a closure plate 'lo which is secured to the block by screws 12.

A pair oi feed wires 'I3 are connected to the lower end of the heating unit and led through a hole '14 into the space between the block G and the cover 28. A conduit 'l5 receives these wires and carries them around the lower one of the block lugs l and thence out of the `instrument housing by way of the saine coupling member 39, that forms a passageway for the feed wires of the signaling system. A pair of posts '16 are mounted in the lower lug 'I and the conduit 15 is tied to these posts by binding cord 11.

The electrical circuit of the heating system is included in the diagrammatic disclosure of Figure 5.

The invention may be embodied in other speciiic forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come. within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:-

1. A dilerential pressure gauge construction comprising a pair of inter-connected pressureresponsive mechanisms; a block for supporting said mechanisms and providing a pair of chambers connected respectively to said mechanisms and each connected to a source of liquid to transmit the pressure of the latter to its corresponding pressure-responsive mechanism; a heating unit common to said chambers to prevent the congelation of any liquid standing in the latter; a recess formed in said block for reception of said heating unit; and a closure plate cooperating with said recess to conceal the heating unit and hold it in position.

2. In combination, in an instrument having indicating mechanism, a housing structure adapted to receive a relatively static liquid for transmitting variations in a given condition to said indicating mechanism, there being a recess formed in a portion of said housing structure, a heating element disposed within and partially lling said recess, and an insulating member fitted between said heating element and the outer surface of said recessed portion to maintain said element in position in the bottom of the recess.

JOSIAH W. PLACE. EMERSON ASCHENBACH. HOWARD J. HARTLEY. 

